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John Dalton
In 1803 an English scientist by the name of John Dalton proposed three atomic theories.
1.All matter was composed of small indivisible particles called atoms
2.Atoms of a given element possess unique characteristics and weight
3.There are three atoms that exist: elements, compounds and complex molecules -
Joseph John Thomson
In 1904 JJ Thomson recommended a model of the atom in a sphere of positive matter in which electrons are positioned by electrostatic forces. He used measurements of scattering light, X, gamma rays, and beta to try and estimate the numbers of electrons in an atom. -
Niels Bohr
Niels Bohr, who is a Danish scientist proposed a theory for the hydrogen atom based on quantum in 1913. His theory is that there should be electrons moving around the nucleus but only in prescribed orbits. When the electrons jump from one orbit to another with a less amount of energy a light quantum is transmitted according to his theory. This theory could be a valid explanation of why atoms transmit or emit light light in fixed wavelengths. -
Robert Millikan
Robert Millikan is well known for his ‘oil drop’ experiment he conducted while he was at the University of Chicago (1913). Robert’s aim of this experiment was to find out the charge of an individual electron. He achieved his experiment by simply dropping oil between electrodes (electrically charged plates) and measuring the force of the droplets passing through the electric field between electrodes. Finally Robert came to a conclusion of the elementary charge of 1.5924(17) x 10^-19C. -
James Chadwick
In 1932 an English scientist by the name of James Chadwick found an important discovery in the domain of nuclear science. This fundamental discovery was the existence of neutrons which is a subatomic particle without an electrical charge. -
Ernest Rutherford
In 1936 Ernest Rutherford, a New Zealand born physicist and chemist discovered the concept of the radioactive wave. He named and differentiated two types of radiations which are alpha and beta radiation. Thanks to this discovery he was credited and known for performing the first split of the atom
